digbyphonic --- research weblog of Jonathan J Digby https://www.digbyphonic.com/ • AUDIO SPECIALIST • RESEARCHER quarto-1.9.37 Sat, 24 Jan 2026 00:00:00 GMT A call for Case Study opportunities Jonathan J Digby https://www.digbyphonic.com/posts/20260124_CaseStudy/ Please consider contributing to a case study if you plan on implementing the author’s Loudness Measures at any of your live events.

NoteLoudness metering for event sound systems – Case study: data gathering guidance

Improved Management of PA System Leq Limits and Off-Site Annoyance

The findings may contribute to the ‘work in progress’ updates of these influential documents:

Technical Document AESTD1007.1.20-05 : Understanding and Managing Sound Exposure and Noise Pollution at Outdoor Events, 2020. [1]

WHO Global Standard for Safe Listening Venues & Events, 2022. [2]

Research paper

Here is a link to the original research:

NoteJ.J. Digby and A.J. Hill, ‘Enhanced Sound Level Monitoring at Live Events by Measuring Audio Program Loudness,’ Proceedings of the Institute of Acoustics, vol. 46, no. 4, pp. 1–8, 2024.

If you would like to discuss any of this, or need further explanation, please get in touch using the contact form , or book an online meeting .

We thank you for your time.

Coloured engraving from 1933 of measuring the sound levels in Paris, 12th March 1933

Image: Measuring the sound levels in Paris, from ‘Le Pelerin’, 12th March 1933 (coloured engraving), Damblans, Eugene (1865-1945) / Private Collection / © Archives Charmet / Bridgeman Images

References

[1]
Hill A, editor. Technical Document AESTD1007.1.20-05 : Understanding and managing sound exposure and noise pollution at outdoor events. 2020 [accessed 2026 Mar 24]. https://www.aes.org/wp-content/uploads/2024/01/AESTD1007_1_20_05-1.pdf
[2]
WHO Global Standard for Safe Listening Venues & Events. 2022 [accessed 2026 Mar 24]. https://iris.who.int/bitstream/handle/10665/352277/9789240043114-eng.pdf?sequence=1
]]> case study audio loudness research live events sound systems https://www.digbyphonic.com/posts/20260124_CaseStudy/ Sat, 24 Jan 2026 00:00:00 GMT Using the DirectOut PRODIGY to manage loudness at live events Jonathan J Digby https://www.digbyphonic.com/posts/20260121_Prodigy/ A self-contained HTML slide deck for using the DirectOut PRODIGY — Multifunction Audio Processor to manage loudness at any upcoming live events. It can be viewed immediately in-browser by clicking the link, or saved for offline access (right-click and save as, or similar).

NoteImproved Management of PA System Leq Limits and Off-Site Annoyance

A loudness metering live event workflow for Public Address systems using DirectOut Technologies PRODIGY

Keyboard navigation for HTML presentation slide deck; MENU is located bottom left
KEY ACTION
→ , ↓ , SPACE , N , L , J next slide
← , ↑ , P , H , K previous slide
E PDF export mode


Also, please consider contributing to a case study if you implement the described Loudness Measures at any of your shows, or otherwise.

NoteLoudness metering for event sound systems – Case study: data gathering guidance

Improved Management of PA System Leq Limits and Off-Site Annoyance

A case study may offer useful contributions to the update of these two influential documents:

Technical Document AESTD1007.1.20-05 : Understanding and Managing Sound Exposure and Noise Pollution at Outdoor Events, 2020. [1]

WHO Global Standard for Safe Listening Venues & Events, 2022. [2]

If you want to chat about this, or have any comments, please don’t hesitate to get in touch:
contact form , or book an online meeting .

Thank you for your time.


Logo for DirectOut Technologies

Logo for University of Derby's Electro-Acoustic Research Laboratory --- EARLab

References

[1]
Hill A, editor. Technical Document AESTD1007.1.20-05 : Understanding and managing sound exposure and noise pollution at outdoor events. 2020 [accessed 2026 Mar 24]. https://www.aes.org/wp-content/uploads/2024/01/AESTD1007_1_20_05-1.pdf
[2]
WHO Global Standard for Safe Listening Venues & Events. 2022 [accessed 2026 Mar 24]. https://iris.who.int/bitstream/handle/10665/352277/9789240043114-eng.pdf?sequence=1
]]> interests audio loudness research case study live events sound systems engineering https://www.digbyphonic.com/posts/20260121_Prodigy/ Wed, 21 Jan 2026 00:00:00 GMT A movie sound effect trope: sound-system feedback Jonathan J Digby https://www.digbyphonic.com/posts/20251212_feedback_sound_effect/ A trope sound effect is ‘a recurrent theme; a motif … to represent or interpret (something) in a figurative or metaphorical way’. [1]

Sound-system feedback—the high-frequency squeal or howling noise—is often used to symbolize a ‘live’ microphone in a public address or broadcast situation. In the majority of these examples the sound-system feedback is figurative.

Examples of sound-system feedback – ‘howlround’, or ‘squeal’ – as a movie sound effect
Title Year Director Timestamp
M*A*S*H 1970 Robert Altman [00:19:30] [00:31:29] [00:38:14] [00:41:34] [00:43:03]
Brubaker 1980 Stuart Rosenberg [00:32:48]
One Magic Christmas 1985 Phillip Borsos [00:14:05] [00:14:43]
Brazil 1985 Terry Gilliam [02:06:53]
Back to the Future 1985 Robert Zemeckis [00:08:14][01:27:06]
Gung Ho 1986 Ron Howard [00:18:33] [00:55:01]
When Harry Met Sally… 1989 Rob Reiner [00:58:28]
Soapdish 1991 Michael Hoffman [00:12:17]
Four Weddings and a Funeral 1994 Mike Newell [00:14:45]
Miss Congeniality 2000 Donald Petrie [00:40:28] [00:41:59] [00:52:54]
Love Actually 2003 Richard Curtis [00:02:26]
Good Bye Lenin! 2003 Wolfgang Becker [00:08:13]
Das Leben der Anderen [The Lives of Others] 2006 Florian Henckel von Donnersmarck [00:12:40]
10 Items or Less 2006 Brad Silberling [00:18:03] [00:18:51]
Hot Fuzz 2007 Edgar Wright [00:55:00] [00:57:36] [00:57:55] [00:58:30]
Semi-Pro 2008 Kent Alterman [00:05:08] [00:09:01]
Synecdoche, New York 2008 Charlie Kaufman [01:27:48] [01:27:58]
Mary and Max 2009 Adam Elliot [00:46:53]
Up 2009 Pete Docter; Bob Peterson (co-director) [00:14:50] [00:14:56] [00:16:44] [00:34:03] [00:35:05 / 00:35:20]
Inside Out 2015 Pete Docter; Ronnie Del Carmen (co-director) [00:54:04]
45 Years 2015 Andrew Haigh [01:23:29]
Coco 2017 Lee Unkrich [00:48:01] [00:50:51] [00:51:00] [00:53:24] [01:21:56] [01:24:54]
Werk ohne Autor [Never Look Away] 2018 Florian Henckel von Donnersmarck [01:36:36]
Booksmart 2019 Olivia Wilde [01:27:01]
Memoir of a Snail 2024 Adam Elliot [01:25:51] [01:26:30]
Wallace & Gromit: Vengeance Most Fowl 2024 Merlin Crossingham, Nick Park [01:02:07]
Nuremburg 2025 James Vanderbilt [02:16:51]
Affeksjonsverdi [Sentimental Value] 2025 Joachim Trier [00:10:08]


Similar tropes:

  • a low-frequency modulated ‘buzz of electricity’ when a magnet is attracted to an object
    e.g. Memoir of a Snail (2024), Adam Elliot [00:29:35]

  • the ‘explosive glass crashing’ which accompanies a 1930s to 1960s-style camera flash bulb combustion
    e.g. Nuremburg (2025), James Vanderbilt [01:15:26] [01:15:43] [01:48:54]

  • the ‘schwing’ of a sharp metal blade that is not necessarily in contact with a substance that would produce this type of sound
    e.g. Im Westen nichts Neues [All Quiet on the Western Front] (2022), Edward Berger [02:12:52]

Movie director's canvas chair and acoustic megaphone

Image: Hand drawn movie theatre drawing illustration_144642320 / Classic film chair / www.freepik.com

References

[1]
Oxford English Dictionary. trope, v., sense 1. Oxford University Press; 2025. https://doi.org/10.1093/OED/3467643930
]]> interests audio https://www.digbyphonic.com/posts/20251212_feedback_sound_effect/ Fri, 12 Dec 2025 00:00:00 GMT ‘Improved Localization for Binaural Recordings and Stereo Program Material Using “Blumlein shuffling”’ Jonathan J Digby https://www.digbyphonic.com/posts/20251203_IoA_paper2/ I had the pleasure of presenting this paper at the Institute of Acoustics’ conference: Reproduced Sound 2025, Harrogate, UK.

NoteJ. J. Digby, A. J. Hill, and B. J. Wiggins, ‘Improved Localization for Binaural Recordings and Stereo Program Material Using “Blumlein shuffling”’, in Reproduced Sound 2025, Harrogate, UK: Institute of Acoustics, 2025.

Anyone short on time but interested enough may wish to skip directly to the audio demonstrations. A self-contained HTML file of the presentation is also available, with informative illustrations:

NoteSelf-contained HTML presentation


[NEXT SLIDE: → , ↓ , SPACE , N , L , J] [PREVIOUS SLIDE: ← , ↑ , P , H , K] [MENU: bottom left]

Abstract

Blumlein’s ‘shuffling’ process was designed to correct spatialization anomalies for ‘stereo’ loudspeaker reproduction of baffled, near ear-spaced omnidirectional microphones.

Without shuffling there is a progressive narrowing of the stereo image as frequency decreases.

At low frequencies the elegant sum-and-difference filter network converts arrival-time differences for an oblique source into amplitude differences.

These low-frequency amplitude differences revert to timing differences at the listener; broadband source localization is preserved.

Its lack of widespread use may be attributed to the commonplace consumption of two-channel stereo program using psychoacoustically unequal reproduction formats: a spaced pair of loudspeakers, binaural earphones, and summed-mono devices – a ‘stereo compromise’.
This paper includes a review of Blumlein’s shuffling process and its application to a hybrid near-coincident microphone technique with a central absorbent baffle.

In addition, the reciprocal shuffling process is investigated for improved binaural earphone reproduction of program material primarily intended for loudspeakers.

Access to audio demonstrations is provided.

Conclusions

  • Two-channel near-coincident microphone techniques have the ability to represent excellent and realistic spatialization and balance of acoustic sources and their environment

  • These features are directly available for binaural earphone reproduction, and readily available for two-channel loudspeaker reproduction via the simplified alt-Blumlein shuffling process —
    ‘Bass sounds are more correctly aligned in direction with the treble, and the overall result has lower listening fatigue and is generally more natural.’ – Michael Gerzon, 1992 [1,p 22]

  • Blumlein shuffling may be considered an essential tool for near-coincident microphone techniques, offering authentic binaural presentation with a pair of stereo loudspeakers

  • Blumlein shuffling’s ability to retain cohesive placement of auditory events can be described as improved ‘locatedness’ 1 — spatial distinction and alignment [3,p 4]

  • Differentiated earphones and loudspeaker versions of ‘stereo’ digital audio formats would allow the audio industries to move beyond the legacy compromise of one version for two non-equal playback conditions.
    A listening device could automatically select its appropriate version through the use of metadata

  • Inverse alt-Blumlein shuffling may be useful for earphone reproduction of commercially-available two-channel ‘stereo’ program material optimized for loudspeakers; (e.g. a built-in option for personal audio players)

  • Inverse alt-Blumlein shuffling provides a more natural earphone listening experience for generic amplitude-panned two-channel ‘stereo’ content – in accordance with Duplex theory [4];
    (e.g. this simple static function may be inserted on a mix-bus output to in-ear monitors)

Supplementary materials

A complete set of audio examples includes binaural earphone and loudspeaker versions of recordings using a baffled near-coincident microphone technique, and earphone demonstrations of inverse alt-Blumlein shuffling applied to commercially available program material.

NoteSupplementary materials page

Thank you for your interest.
Feedback is encouraged.

Mr Jonathan Digby (Principal investigator)
Researcher

References

[1]
Gerzon M. Applications of Blumlein Shuffing to Stereo Microphone Techniques. In: AES 93rd Convention. San Francisco; 1992. https://aes.org/publications/elibrary-page/?id=6939
[2]
Blauert J. Sound Localization in the Median Plane. Acta Acustica united with Acustica. 1969 [accessed 2026 Mar 25];22. https://www.researchgate.net/publication/263716618_Sound_Localization_in_the_Median_Plane
[3]
Blauert J. Spatial Hearing: The Psychophysics of Human Sound Localization (Revised Edition). 1996. https://doi.org/10.7551/mitpress/6391.001.0001
[4]
Hartmann WM, Rakerd B, Crawford ZD. Localization of sound in rooms VI: Duplex theory. The Journal of the Acoustical Society of America. 2025;158(3):2048–2061. doi:10.1121/10.0039111



Logo of the Institute of Acoustics

Logo for University of Derby's Electro-Acoustic Research Laboratory - EARLab

Footnotes

  1. From Jen Blauert’s superb Spatial Hearing (1996): ‘We introduce the new term “locatedness” for the spatial distinction in order to avoid certain misunderstandings that might arise from use of “localization” at this point [2].’↩︎

]]> PGR activities research published Blumlein shuffling near-coincident microphones stereophonic binaural https://www.digbyphonic.com/posts/20251203_IoA_paper2/ Wed, 03 Dec 2025 00:00:00 GMT Fair loudness-based measures for live events - a client proposal Jonathan J Digby https://www.digbyphonic.com/posts/20250521_FairLoudness-basedMeasuresProposal/ Announcing a short introduction to the Fair Loudness-based Measurement protocol written for live event producers and relevant stakeholders.
Right-click link to download the self-contained HTML presentation, or view in browser:

Fair loudness-based measures for live events —
Proposal for live event producers and relevant stakeholders

Keyboard navigation for HTML presentation slide deck; MENU is located bottom left
KEY ACTION
→ , ↓ , SPACE , N , L , J next slide
← , ↑ , P , H , K previous slide
E PDF export mode
Tip

The above link is a self-contained HTML file. It may be viewed online, or downloaded for offline viewing.

Further information

A companion presentation with detailed instructions is available here.
The original research paper is available here.

Please contact the author if you would like further information.

Thank you!

Vintage photograph of two women measuring their yodelling level with a meter

Image: Women Yodelling with Yodelling Meter (photograph) / Everett Collection / Bridgeman Images

]]> PGR activities research presentation https://www.digbyphonic.com/posts/20250521_FairLoudness-basedMeasuresProposal/ Tue, 20 May 2025 23:00:00 GMT Fair loudness measures for live events Jonathan J Digby https://www.digbyphonic.com/posts/20250331_FairLoudnessMeasures/ I have written an HTML presentation to accompany our research paper.
It’s linked toward its useful application with HELA Certified events.
Right-click link to download the self-contained HTML file, or click link to view in browser:

Fair loudness measures for live events —
Explanation, setup, and instructions

Keyboard navigation for HTML presentation; the presentation MENU is located bottom left
KEY ACTION
→ , ↓ , SPACE , N , L , J next slide
← , ↑ , P , H , K previous slide
E PDF export mode
Work in progress

A number of case studies using our research paper recommendations are planned for the summer of 2025.
The findings will be used to improve and expand specific guidance for implementing our protocol.

Please contact the authors if you are interested in collaborating with us and using your event as a case study.

Thank you!

J.J. Digby and A.J. Hill, ‘Enhanced Sound Level Monitoring at Live Events by Measuring Audio Program Loudness,’ Proceedings of the Institute of Acoustics, vol. 46, no. 4, pp. 1–8, 2024.


Logo for University of Derby's Electro-Acoustic Research Laboratory - EARLab

]]> PGR activities research presentation https://www.digbyphonic.com/posts/20250331_FairLoudnessMeasures/ Sun, 30 Mar 2025 23:00:00 GMT Audio Test Signals – Brownian noise Jonathan J Digby https://www.digbyphonic.com/posts/20250323_LUFS_testsignals/ Additional Content: Audio Test Signals for Acoustical Alignment, Listening Level

Once sound system optimization is completed propagation tests should be conducted with appropriate test signals and loudness normalized programme material at a pre-calibrated output level of ‘0 LU’ in ‘EBU mode’ –23 LUFS.[1]

A recommended type of test signal is broadband Brownian noise, as this has a frequency spectrum that approximates real musical material. The following WAV files were prepared with Audacity audio editing software:

Brownian Noise STEREO -23 LUFS non-coherent L&R 48 kHz.wav

Brownian Noise STEREO -23 LUFS non-coherent L&R 44,1 kHz.wav

Brownian Noise MONO -23 LUFS 48 kHz.wav

Brownian Noise MONO -23 LUFS 44,1 kHz.wav

All loudspeakers should be operational during the propagation test, with the overall acoustic gain adjusted to fit local conditions.
N.B. This differs from R 128 Acoustical Alignment, Listening Level instructions in EBU TECH 3343, pp. 22–23.

Fair Loudness Measures for Live Events

To accompany the instructional presentation (see link below).
Right-click link to download the self-contained HTML file, or view in browser:

NoteFair loudness measures for live events — Explanation, setup, and instructions

Keyboard navigation for HTML presentation slide deck; MENU is located bottom left
KEY ACTION
→ , ↓ , SPACE , N , L , J next slide
← , ↑ , P , H , K previous slide
E PDF export mode

Case studies

Please contact the authors if you are interested in collaborating with us and using your event as a case study. The findings will be used to improve and expand specific guidance.

NoteLoudness metering for event sound systems – Case study: data gathering guidance

Improved Management of PA System Leq Limits and Off-Site Annoyance

Thank you!

Graphic representation of Brownian motion travel

Image: Brownian motion (litho), English School, (20th century) / Private Collection / © Look and Learn / Bridgeman Images

References

[1]
European Broadcasting Union. TECH 3343: Guidelines for Production of Programmes in Accordance with EBU R 128. 2023 [accessed 2026 Mar 31]. https://tech.ebu.ch/docs/tech/tech3343.pdf
]]> PGR activities research audio files https://www.digbyphonic.com/posts/20250323_LUFS_testsignals/ Sun, 23 Mar 2025 00:00:00 GMT On-campus, w/c 2025-01-27 Jonathan J Digby https://www.digbyphonic.com/posts/20250131on-campus20250127/ Here are the planned on-campus locations for my next round of experimental preparation work, in-room loudspeaker measurements, and audio recordings.
Faculty and student cohort interested in assisting, observing, enquiring, or critiquing are welcome to attend without obligation.

  • Please use the Contact link to send your name, date, and time(s) you would like to attend.
  • My intention is to update locations and times on this page as the week unfolds.
  • Subscribe to the RSS feed to keep track of updates. (How to subscribe to an RSS Feed)
day time location
2025-01-27 10:00 / 13:00 MS036/037 Hemi-anechoic
2025-01-27 16:30 / 19:30 MS036/037 Hemi-anechoic
-
2025-01-28 08:30 / 12:50 MS036/037 Hemi-anechoic
2025-01-28 11:00 / 20:00 MS005
-
2025-01-29 08:30 / 10:30 MS036/037 Hemi-anechoic
2025-01-29 10:30 / 12:00 MS102C
2025-01-29 14:00 / 17:30 MS102C
-
2025-01-30 09:00 / 10:00 MS036/037 Hemi-anechoic
2025-01-30 10:00 / 14:30 MS018
2025-01-30 14:30 / 16:00 MS036/037 Hemi-anechoic
2025-01-30 16:00 / 20:00 MS005
-
2025-01-31 08:30 / 10:30 MS102A
2025-01-31 10:30 / 12:00 MS036/037 Hemi-anechoic
2025-01-31 14:00 / 16:00 Sound Studios



Thank you!

University of Derby's coat of arms

University of Derby

]]> PGR activities research https://www.digbyphonic.com/posts/20250131on-campus20250127/ Fri, 31 Jan 2025 00:00:00 GMT ‘Enhanced Sound Level Monitoring at Live Events by Measuring Audio Program Loudness’ Jonathan J Digby https://www.digbyphonic.com/posts/20241124_IoA_paper/ Concerts and events can use a Target Level loudness to optimize sound exposure by ensuring parity of loudness between acts and show elements (broadband loudness normalization). This is not the case when using an limit (A-weighted peak normalization).

NoteJ.J. Digby and A.J. Hill, ‘Enhanced Sound Level Monitoring at Live Events by Measuring Audio Program Loudness,’ Proceedings of the Institute of Acoustics, vol. 46, no. 4, pp. 1–8, 2024.


The main benefit for stakeholders is parity of loudness across all show elements and acts – using a fairer, psychoacoustically correct measure. It’ll be useful to calibrate an electrical signal to , but what may be more beneficial is the improvement in sound quality.
Dr Bruce Wiggins PhD FHEA MAES PGCHE


Logo of the Institute of Acoustics

Logo for University of Derby's Electro-Acoustic Research Laboratory - EARLab

]]> published research loudness SPL https://www.digbyphonic.com/posts/20241124_IoA_paper/ Tue, 12 Nov 2024 00:00:00 GMT On-campus, w/c 2024-09-30 Jonathan J Digby https://www.digbyphonic.com/posts/20241004on-campus20240930/ Here are the planned on-campus locations for my next round of experimental preparation work, in-room loudspeaker measurements, and audio recordings.
Faculty and student cohort interested in assisting, observing, enquiring, or critiquing are welcome to attend without obligation.

  • Please use the Contact link to send your name, date, and time(s) you would like to attend.
  • My intention is to update locations and times on this page as the week unfolds.
  • Subscribe to the RSS feed to keep track of updates. How to subscribe to an RSS Feed
day time location
2024-09-30 10:00 MS228
2024-09-30 16:30 / 19:30 MS036/037 Hemi-anechoic
-
2024-10-01 08:30 / 12:50 MS005
2024-10-01 13:30 / 17:30 MS039 Auditorium 3
-
2024-10-02 08:30 / 11:45 MS102C
2024-10-02 12:00 / 13:00 Ms039: Interview and Q&A
2024-10-02 14:00 / 17:30 MS036/037 Hemi-anechoic
-
2024-10-03 09:00 / 13:00 MS039 Auditorium 3
2024-10-03 13:30 / 16:00 MS036/037 Hemi-anechoic
2024-10-03 16:30 / 20:30 MS102C
-
2024-10-04 08:30 / 12:00 MS036/037 Hemi-anechoic
2024-10-04 12:15 / 17:20 MS005



Please let me know if you plan on making it to any of the sessions.
Thank you!

Logo for University of Derby's Electro-Acoustic Research Laboratory - EARLab

]]> news PGR activities https://www.digbyphonic.com/posts/20241004on-campus20240930/ Sun, 29 Sep 2024 23:00:00 GMT